Experimental detection of boundary diffraction waves irradiated by an impulsively excited line source of finite length

Abstract

It has been shown theoretically that the transient acoustic pressure field radiated by a finite line source comprises three distinct components: a spatially discontinuous cylindrical wave (“geometrical wave”) and two directional boundary-diffraction waves radiated by the ends of the line. This model of the structure of the pressure field, which is that predicted by the Rubinowicz-Maggi diffraction theory, has also been demonstrated experimentally. The experiments were conducted in a water tank. Bursts of pseudorandom band-limited white Gaussian noise were used to impulsively excite a line transducer electrically. By crosscorrelating these signals with the acoustic signals that the transducer radiates, and by using a computer to filter the resulting crosscorrelation functions, the waveform of the transducer's spatial impulse response was obtained at a number of observation points in the source transducer's radiated field. The experimentally obtained waveforms agree closely with those predicted by the theoretical calculations.